168 



POACEAE 



3. Trisetum canescens Buckl. 

 Tall Trisetum. Fig. 379. 



Trisetum canescens Buckl. Proc. Acad. Phila. 1862: 100. 1863. 



Culms erect, or decumbent at base, 60-120 cm. tall ; 

 sheaths more or less retrorse-pilose, at least the lower, 

 and often also canescent; blades flat, scabrous or 

 canescent ; panicle narrow, loose, sometimes inter- 

 rupted and spikelike, 10-20 cm. long ; glumes smooth, 

 except the keel, strongly unequal, the first narrow, 

 acuminate, 1-nerved, the second broad, acute, 3- 

 nerved, longer than the first, 5-7 mm. long ; lemmas 

 firm, scaberulous, the upper exceeding the glumes, the 

 teeth aristate ; awns geniculate, spreading, exserted, 

 more or less twisted below, attached one-third below 

 the apex, usually about 12 mm. long. 



Mountain meadows, moist ravines, and along streams, 

 Transition Zone; British Columbia to Montana and south in 

 California to Santa Cruz and Tulare Counties. July-Aug. Type 

 locality: Columbia Plains of Oregon. 



4. Trisetum spicatum (L.) Richt. 

 Downy Oat-grass. Fig. 380. 



Aira spicata L. Sp. PI. 64. 1753. 



Aira subspicata L. Syst. Nat. ed. 10. 2: 873. 1759. 



Avena mollis Michx. Fl. Bor. Am. 1: 72. 1803. 



Trisetum subspicatum Beauv. Ess. Agrost. 88. 1812. 



Trisetum subspicatum molle A. Gray, Man. ed. 2. 572. 1856. 



Trisetum spicatum Richt. PI. Eur. 1: 59. 1890. 



Culms erect, rather stout, 15-50 cm. tall, smooth or 

 puberulent; sheaths and usually the blades puberulent ; 

 panicle dense and spikelike, pale or often dark-purple, 

 5-15 cm. long; spikelets 4-6 mm. long; glumes some- 

 what unequal in length, smooth except the keels, the 

 first narrow, acuminate, 1-nerved, the second broader, 

 3-nerved, acute ; lemmas scaberulous, 5 mm. long, the 

 first longer than the glumes, the teeth setaceous; awns 

 geniculate, exserted. 



A characteristic grass of high altitudes, mostly in the Alpine 

 Zone; arctic regions of the northern hemisphere, southward in 

 the higher mountains to the southern hemisphere. Found on 

 high mountains up to the limit of vegetation. July-Aug. Type 

 locality, European. 



5. Trisetum sesquiflorum Trin. 

 Congdon's Trisetum. Fig. 381. 



Trisetum sesquiflorum Trin. Mem. Acad. St. Petersb. VI. Sci. 



Nat. 2': 14. 1836. 

 Trisetum congdoni Scribn. & Merr. Bull. Torrev Club 29: 470. 



1902. 



Resembling T. spicatum, but differing in having 

 smooth sheaths and blades, the latter usually flat but 

 sometimes involute, and in having wider panicles and 

 larger spikelets, 8 mm. long. 



Meadows and slopes of the Alpine Zone; Alaska to Cali- 

 fornia in the Sierra Nevada to .Sequoia National Park. July- 

 Aug. Type locality: Kamchatka. 



Trisetum flavescens (L.) Beauv., a European species, occa- 

 sionally introduced in tlie eastern States, has been found at 

 Blue Lake, California (Tracy). It differs from T. canescens 

 in the relatively broader and more open yellow panicle. 



